Your 60 ml inks will be more than enough you get you started and running for many months, unless you are printing 50+ 8x10's per day--or~50 sq ft. Now that you are using an inexpensive hi quality ink, DON'T hesitate to switch between photo blk and matte blk more often; each swap will cost ~50 cents.
Your carts will take 70-75 ml, 60 is no problem--you can take the effort to use some the ink remaining in your larger carts.
I further suggest that you prime the cart using the priming port (white plug) just in front of the ink exit port, I'm concerned about damage to the spring loaded exit port. It's OK to use the small accessory tip to remove ink from an 'empty 10-15 ma' OEM cart but not worth the potential damage by using it to prime the cart-plus it is much easier.
Do remember in an emergency you can always directly swap a bought/borrowed OEM cart for a refillable cart and complete your print session.
good luck irv weiner